Draft regulator



Spt. 17, 1957 A. H. ZIPH DRAFT. REGULATOR Filed Aug. 165 1954 INVENTORQ firm raw fi Zkf) Q WZWW United States Patent O DRAFT REGULATOR Andrew H. Ziph, St. Joseph, Mo., assignor to Walker Manufacturing and Sales Corporation, St. Joseph, Mo., a corporation of Missouri Application August 16, 1954, Serial No. 449,925

1 Claim. (Cl. 236-45) This invention relates to new and useful improvements in draft regulators for combustion apparatus, and has particular reference to draft regulators of the barometric type which, once set for the desired draft, will automatically maintain the desired draft despite variations in the natural or stack draft. Certain types of combustion apparatus, notably certain oil burners, are quite sensitive to magnitude of draft, and require substantially constant draft for eflicient operation. In general, this type of draft regulator contemplates a draft-relieving opening in the flue pipe or stack connection of the combustion apparatus, said opening being regulated by a damper which is movable responsively to variations in the stack draft to admit greater or smaller quantities of air.

An important object of the present invention is the provision of a draft regulator of the type described wherein the damper door is hung pivotally on a horizontal axis, and having a counterweight carried movably by said door whereby to adjust the draft force necessary to open said door, and having novel means whereby to protect the adjusting mechanism for moving said counterweight from sticking or jamming by reason of the dust and soot customarily present inv the air passing through the regulator, and wherein said protecting member serves also as an operating element in the functioning of said adjusting mechanism.

Other objects are simplicity and economy of structure, and efliciency and dependability of operation.

With these objects in view, as well as other objects which will appear in the course of the specification, reference will be had to the drawing, wherein:

Fig. l is a front elevational view of a draft regulator embodying the present invention, shown in its closed position.

Fig. 2 is a sectional view taken on line 11-11 of Fig. 1.

Fig. 3 is a fragmentary sectional view taken on line IIIIII of Fig. 2.

Fig. 4 is a sectional view taken on line IV--IV of Fig. 1.

Fig. 5 is an enlarged fragmentary sectional view taken on line V-V of Fig. 3 with parts left in elevation.

Like reference numerals apply to similar parts throughout'the several views, and the numeral 2 applies to a horizontal pipe adapted to be interconnected at one end to the flue pipe or stack connection, not shown, of a combustion apparatus, and carrying the draft regulator, designated generally by the numeral 4, at its opposite end. Said regulator includes an open cylindrical ring 6 inserted frictionally into pipe 2, said ring having a rearwardly facing external peripheral shoulder 8 which limits the insertion of said ring into said pipe. The inner diameter of said ring defines an air inlet opening 10, which is normally substantially closed by a generally planar circular damper door 12. Said door is pivotally supported in said opening by a pair of pivot pins 14. Said pins are horizontal and coaxial, being disposed in the plane of the door at opposite sides thereof, and above the center thereof. The enlarged outer end 16 of each pin is threaded in ring '6, and the inner end thereof lies pivotally in a groove 18 stamped in the door, and retained therein by a small clip or bracket 20 welded or otherwise fixed to the forward face of said door.

The door axis defined by pivot pins 14 divides the door 12 into an upper or minor segment and a lower or major sector. It is apparent that a current of air against the outer face of the door induced by the draft vacuum within pipe 2 will cause the lower segment of the door to swing inwardly, thereby partially uncovering the air inlet opening 10 and admitting air to the pipe 2 and thence to the flue pipe (not shown), thus partially relieving the draft in the combustion apparatus. The movement of the door will be substantially proportional to the stack draft, and the combustion chamber draft will thus be maintained substantially constant despite variations in the stack draft. The lower segment of the door is prevented from swinging outwardly by a pair of fingers 22 formed integrally with ring 6 and overlapping the outer face of door 12. Each of said fingers carries a rubber bumper 24 which engages the outer face of door 12 below its pivotal axis, when the door is in its closed position. The outward swinging movement of the upper door segment, during the automatic operation above described, is limited by a finger 26 formed integrally with ring 6 and overlapping the outer face of the door substantially at the level of one of pivot pins 14.

Adjustment of the regulator to provide different drafts is accomplished by the mechanism best shown in Fig. 5. A tubular sleeve 28 is fixed at its forward end in the upper segment of door 12, and extends inwardly therefrom and at right angles to the plane thereof. A stem 30 has a smooth cylindrical bearing portion 32 carried rotatably in sleeve 28. Inwardly of said sleeve, said stem is enlarged and has multiple threads formed therein to constitute a screw 34, the shoulder 36 between screw portion 34 and bearing portion 32 abutting the inner end of sleeve 28. Bearing portion 32 extends forwardly of door 12, and is still further reduced to form a threaded extension 38. A packing washer 40 of felt or other suitable material is carried on the forward end of stem portion 32, bearing against the forward face of door 12. Carried on the threaded stem extension is a planar pointer finger 42 having a hole 44 formed therein fitting loosely but non-rotatably on the stem, a lock washer 46, and a knurled adjusting knob 48. Finger 42 extends radially of the stem. Tightening knob 48 compresses the packing washer against the forward face of the door, loading the stem frictionally to prevent accidental rotation thereof, and sealing the stem bearing against the entry of dust, soot, or the like.

A planar, segmental counterweight 50 is carried on screw 34, said counterweight having a press-fitted insert 52 internally threaded to engage the threads of the screw. Said counterweight is movable toward and from the door by turning knob 48. A dust cover 54 having the form of a forwardly opening cup is secured to the inner face of door 12 so as to completely enclose the counterweight and screw, said cover being provided at its forward edge with tabs 56 which are welded or otherwise fixed to the inner surface of the door. This dust cover serves to protect the screw connection between the screw and counterweight from the accumulation of dust, soot, and the like. The cross-sectional shape of the cover is segmental, corresponding to the shape of the counterweight, whereby to prevent said counterweight from turning with screw 34 when said screw is turned by knob 48. A pair of ribs 58 formed in the bottom wall of the cover form the only points of contact between the cover and the counterweight, and hence serve to ease the movement of the counterweight. Moreover, the rear wall 60 of the cover is disposed in close proximity to the rearward end of screw 34- thus preventing the counterweight from being threaded off of the end of the screw.

The weight of the upper segment of the door, plus the weight of the parts carried thereby, is less than the weight of the lower segment of the door, whereby the door will always return to its closed position, as shown in Fig. 2. Furthermore the parts are so proportioned that when the door is closed, and weight 50 is disposed in its closest relation to the door, a very slight closing movement is exerted on the door. This setting should correspond to the minimum draft required by the combustion apparatus, and may actually closely approach actual balance of the door. It will be noted that portions 62, 64 and 66 of the door are olfset forwardly from the principal plane of the door. These ofisets stiffen the door, and may also be decorative in character. Also, since the offsets are disposed forwardly of the door axis, they partially offset the mass of counterweight 50, which is disposed rearwardly of said axis, thereby permitting a closer approach to actual vertical balance of the door. Ofiset 66, which corresponds in shape to counterweight 50, also permits a closer approach of the counterweight to the principal plane of the door.

It is obvious that when knob 48 is turned to move counterweight 50 inwardly or rearwardly along screw 34, the closing moment exerted on the door thereby will be increased, whereby a greater force will be required to swing the door open, and a greater draft will be maintained at the combustion apparatus. The setting of the weight is indicated by the angular position of finger 42, which may be read in relation to suitable indicia 68 imprinted on the outer face of door 12.

A bolt 70 and enlarged nut 72 are secured in door 12 adjacent the bottom edge thereof. It is useful in installations where the pipe 2 is connected into a vertical flue pipe and is so short that the lower edge of the door, when open, projects into the stream of combustion gases in the flue pipe. In such installations the flue gases impinge 4 upon the door and tend to disturb the setting of the door for the desired draft. Bolt and nut -72 counteract this effect.

While I have shown and described a specific embodiment of my invention, it will be apparent that various minor changes of structure and operation could be made without departing from the spirit of the invention as defined by the scope of the appended claim.

What I claim as new and desire to protect by Letters Patent is:

A draft regulator comprising a frame ring defining an air inlet opening, a circular damper door of a size to substantially close said opening, said door being pivotally mounted in said ring on a horizontal axis lying in the plane of said door and above the center thereof to divide said door into upper and lower segments, a bearing mounted in the upper segment of said door, a stem carried rotatably in said bearing and extending through said door normally thereto, a screw fixed on one end of said stern, a counterweight threaded on said screw, and a dust cover fixed to said door and enclosing said screw and counterweight, said counterweight being non-circular in a plane at right angles to said screw and said cover being formed in a corresponding shape in the same plane, whereby rotation of said counterweight with said screw is prevented, a wall of said dust cover parallel to said screw having ribs formed therein whereby to engage said counterweight slidably.

References Cited in the file of this patent UNITED STATES PATENTS 2,159,033 Leonard May 23, 1939 2,289,196 Hutterer July 7, 1942 FOREIGN PATENTS 129,876 Austria Oct. 10, 1952 ninth-H 

